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Ecotoxicological information

Toxicity to soil microorganisms

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Description of key information

No data on the toxicity to soil organisms is available.

Key value for chemical safety assessment

Additional information

Two studies are available in order to examine the terrestrial toxicity potential of the test substance. In a study on terrestrial plants a NOEC > 1000 mg/kg dw of soil was observed concerning the seedling emergence and the growth of three different plant species. In a 56 days-reproduction study on earthworms a NOEC for reproduction of 250 mg/kg dw of soil was observed. The EC50 of the test substance on the reproduction of earthworms was determined to be 412 mg/kg dw of soil.

It can be assumed that earthworms are the terrestrial organisms showing the most sensitive reaction to the test substance. This assumption is substantiated by the results of the study on terrestrial plants. The more sensitive reaction of earthworms can be traced back to the habit of earthworms to ingest soil particles in order to fulfill their nutrition needs. This is of great advantage because the organisms get exposed to an additional exposure pathway.

In contrary to earthworms, the test substance is likely to be less bioavailable to terrestrial microorganisms. This is because they mainly get in contact with the pore water or the solid soil phase, respectively, but they do not ingest the compound. Since the earthworm reproduction study resulted in a relatively high NOEC, an even higher NOEC for terrestrial microorganisms can be assumed.

Based on these data and the low toxicity of the test substance to aquatic microorganisms (EC20 = 99 mg/L, EC50 = 356 mg/L, NOEC = 74 mg/L), the risk to terrestrial microorganisms is also expected to be low. Therefore, a toxicity study on soil microorganisms is not provided.